298 Nutrition of Vegetables. 
not determined ; *57 gr. of oxyde of iron ; and a very small por- 
tion of magnesia. 
Exp. II. In a very large, deep, and perforated bowl of stone 
ware, filled with well washed flowers of sulphur, 250 seeds of 
white mustard were sown. The whole was covered with a large 
bell glass, allowing free access to the air and light. The plants 
grew vigorously, being frequently watered with distilled water; 
as sulphur, having little affinity with water, parts with it very 
easily, and dries on the surface. They produced flowers in tol- 
erable abundance, and the seeds produced plants in common 
ground. The weight of the fresh plants, with the fallen leaves, 
was 108 gr. ; and when dried 18*6 gr. Their coal weighed 7*8 
gr. and left 1-55 gr. of whitish ashes, which afforded by lixivia- 
tion *6 gr. of carbonate and sulphate of potash. The insoluble 
part was similar to that of the former. 
Exp. III. A hundred seeds of white mustard were sown in 
twenty pounds of very small unglazed shot, on the 9th of July. 
On the 28th of August they began to flower, and afforded small 
pods. All these plants were slender, and had but few and small 
leaves. When fresh they weighed 10 gr. and after being dried 
2.3 gr. they yielded very little coal, but more than the weight of 
the seed. The weight of the shot appeared to oppose too great 
an obstacle to the young roots, as most of them spread over the 
surface, without being able to penetrate it. The little affinity of 
the lead for water was another reason of the feeble growth of the 
plants ; and hence I have found, that plants thrive less in metallic 
powders, than in their oxyds. 
Exp. IV. On a flat stone pavement a bed was formed, about a 
yard high, of fine sand, taken immediately from the bed of the 
river, and well washed. In this were sown seeds of the common 
radish ( rajihanus sativus ) which were frequently watered with 
perfectly pure rain water, and the plants grew with as much vi- 
gour as they would have done in any ground. The greater part 
of the radishes were brought to table, and were of a very delicate 
flavour, without any of the disagreeable earthy taste they have 
sometimes. Some of them were left to seed ; and most of these 
grew to the height of 2 feet or 2|-. It was observed, that those at 
the top of the heap were much larger and stronger than those 
near the bottom.* 
* A skilful gardener informs me, that asparagus too will succeed very well 
in pure river sand. Potatoes also grow well in sand, and are said to be better 
tasted. 
